The present invention relates to processors in general, especially to continuous developing machines for exposed photographic paper or the like, and more particularly to improvements in developing machines wherein at least one of a battery of tanks for storage of liquid baths receives a liquid replenisher at regular or irregular intervals.
The quality of exposed photographic paper or films is affected by variations in temperature of the photochemical developing bath or baths. It is desirable to insure that the temperature remains constant or fluctuates within an extremely narrow range. Therefore, many presently known developing machines comprise heating devices for some or all of the liquid baths, and means for regulating the heating action of such devices. The regulating means is intended to insure that the temperature of each heated liquid bath will remain within a desired range. A drawback of presently known developing machines is that the temperature of the bath fluctuates within a much wider range if the quantity of material to be processed varies, e.g., when the number of photographic films or photographic paper strips which are transported simultaneously increases or decreases as well as when relatively narrow strips or webs of photographic film or paper are followed by wider strips or vice versa. Still further, the temperature of a bath will change if the speed at which one or more strips are transported therethrough is changed. Fluctuations of bath temperature under the just outlined circumstances are attributable, to a considerable degree, to the need for addition of replenisher in quantities which vary as a function of the quantity of material passing through a bath per unit of time. The temperature of the replenisher is normally different from the temperature of the bath or from the desired temperature of the bath. Heretofore known attempts to maintain the temperature of the bath close to the desired value include the provision of regulators having mobile pointers which engage or are disengaged from electric contacts at different temperatures and are associated with thermorelays. Such devices are incapable of changing the temperature practically immediately after the temperature begins to deviate from an optimum range. Moreover, the energy requirements of conventional regulating devices are extremely high.